Contributors :Gourab Majumdar

Chief Engineer, Power Device Works, Mitsubishi Electric Corporation, Japan

John DonlonSenior Application Engineer, Powerex Inc., U.S.A.

Eric MottoPrincipal Application Engineer,Powerex Inc., U.S.A.

Tatsuo OzekiProject Manager, SiC Project Group, Advanced Technology R & D Center, Mitsubishi Electric Corporation, Japan

Hidekazu YamamotoManager, Power Device Development Dept., Power Device Works, Mitsubishi Electric Corporation, Japan

Makoto SetoManager, Power Electronics System Development Center, Advanced Technology R & D Center, Mitsubishi Electric Corporation, Japan

Abstract:At Mitsubishi, R & D work on SiC Power Devices has been continuing for several

years through implementation of in-house strategic projects and by active participation in national projects in Japan. Through these activities, advanced high performance MOSFET and Schottky Barrier Diode devices of 1200V-2000V class have been developed.

In this presentation, the technical results of these activities will be briefly explained. The conceptual aspects and performance-related evaluation results of some experimental SiC-MOSFET and SiC-SBD device structures will be shown.

It will conclude with some discussion of existing issues and possibilities concerning SiC power devices becoming the future de facto solution in the industry.

Present Status And Future Prospects of SiC Power DevicesPresent Status And Future Prospects of SiC Power Devices

IntroductionIntroductionDevice Achievements & NeedsDevice Achievements & NeedsFuture Prospects of SiC Power DevicesFuture Prospects of SiC Power DevicesConclusionConclusion

Present Status And Future Prospects of SiC Power DevicesPresent Status And Future Prospects of SiC Power Devices

1950 1970 1980 1990

Triac

ThyristorLight Trig. Thyristor

GTO

SITBipolar Tr. Module

High βBip. Tr. Module

2000

First Wave(Uncontrollable

Latching Devices)

Second Wave(ControllableNon-Latching

Devices)

Third Wave(MOS-GateControlled Devices & Power ICs)

Bipolar Transistor

Trench MOS

Sub µm MOS1991 : Second Generation MOSFET & IGBT

(5μm design rule).1993 : Third Generation MOSFET & IGBT

(3μm design rule).1995 : Fourth Generation MOSFET

(1.5μm design rule).1995 : Fourth Generation IGBT

(1μm design rule; Trench Version).1997 : Fifth Generation MOSFET

(1μm design rule).1999 : Fourth Generation IGBT

(1μm design rule; Planar Version).

1991 : Second Generation MOSFET & IGBT(5μm design rule).

1993 : Third Generation MOSFET & IGBT(3μm design rule).

1995 : Fourth Generation MOSFET(1.5μm design rule).

1995 : Fourth Generation IGBT(1μm design rule; Trench Version).

1997 : Fifth Generation MOSFET(1μm design rule).

1999 : Fourth Generation IGBT(1μm design rule; Planar Version).

GCT

IGBT

*Note: ASIPM ≡ Mitsubishi’s Application Specific Intelligent Power Module.CSTBT ≡ Mitsubishi’s Carrier stored trench gated bipolar transistor.“..Generation” ≡ The denominations refer to Mitsubishi’ s technologies.

IGBTModule

Trench IGBT

IPM;ASIPM *Note;

DIP-IPM;HEV-IPM;HVIPM;

Power ICs

System Integrated Solutions

CSTBTTM *Note

IPM Introduction by MitsubishiIPM Introduction by Mitsubishi

Evolution of Power DevicesEvolution of Power Devices

TM New Devices(SiC Devices)

Sub µm IGBT

Power MOSFET Power MOS. Module

RC Thyristor

1st Gen 2nd Gen.

E series3rd Gen.H series

4th Gen.F series

5th Gen.NF series

Device usingnew material

Power losses in inverter application

1985 1990 1995 2000 2005

Overall power loss reduced to 1/3

Pow

er L

oss

(W)

100100WW

1st Gen.

IGBT conduction

loss

Planar gate Trench gate

IGBT turn-off

loss

2nd Gen. 3rd Gen. 4th Gen. 5th Gen.

7575WW

5050WW4040WW 3333WW

Reduction of IGBT operation losses

Simulated ConditionsDevice Ratings = 75A, 600V

Inverter Output Current,Io = 45Ar.m.s.

Carrier frequency,fc = 15kHzPower factor, φ = 0.8

Application : VVVF Inverter Circuit

Control Scheme = PWM, Sinusoidal

IGBT turn-on

loss

CSTBTTM

0.1

1

10

100

1000

10 100 1000 10000

Breakdown Voltage　(V)

Spe

cific

Ron

(moh

m-c

m2)

Power MOSFET

Silicon Unipolar Limit

Compared at Tj or Tch = 400K

Super Junction MOSFET

CSTBTTM

IGBT-2G IGBT-3G

HV-IGBT

HV-Thyristor/GTO family

Static characteristics of Si & SiC devices compared with theoretical limitsRelationship between specific on-resistance and breakdown voltage

Super JunctionUnipolar Limit (Estimated for Jp=1μm）

EstimatedPiN Diode Limit (Bipolar)

4H-SiC Unipolar Limit

In terms of power losses, the users have benefited from continuous improvement made by various generations of IGBT families over the past 20 years

0.01

0.1

1

10

100

1980 1990 2000 2010 2020

年

パワー密度　[W/cc]

M-Converter（RB-IGBT)

Power Density Enhancement for Medium Power PE EquipmentPower Density Enhancement for Medium Power PE EquipmentPower Density Enhancement for Medium Power PE EquipmentPo

wer

Den

sity

(w

/cc)

Year

Gen-purpose Inverter( Bipolar )

Gen-purpose Inverter( IPM )

Gen-purpose Inverter( DIP-IPM )

HEV Inverter( EV-IPM )

Gen-purpose Inverter( RC-IGBT & others )

M-ConverterInverterHEV Inverter •• Efforts toward Efforts toward SiC Application SiC Application

•• Integration Integration TechnologyTechnology

•• New Packaging New Packaging TechnologiesTechnologies

Note:IPM: Intelligent Power ModuleDIP-IPM: Dual In-line Package IPMEV-IPM: IPM for EV and/or HEV applicationsRB-IGBT: Reverse Blocking type IGBTRC-IGBT: Reverse Conducting type IGBTM-Converter: Matrix ConverterHEV Inverter: Inverter systems for hybrid vehicles

n- Si drift layer(very low carrier concentration)

n+ p

n-

n+p

source

～～～～ Si substrate

n+ pn-n+p

～～

～～ SiC substrate

n-SiC drift layer

SiC

= Drastic reduction of On-state Loss

E

drift layer thickness: very thinSi

SiC

Comparison of Device Structure andDistribution of Electric Field

Comparison of Device Structure andDistribution of Electric Field

Distribution ofelectric field

carrier concentration: very high

SiBreakdown Electric Field x 10

source sourcesourcegate gate

drain

drain

Crit

ical

Ele

ctric

al B

reak

dow

n Fi

eld

[MV

/cm

]

Bandgap [eV]

0

4

32

1

1

2

3

54

5

6

6

Si

Diamond

4H-SiC

6H-SiC3C-SiC

SiC Poly types

Wide bandgapWide bandgapHigh critical BVHigh critical BV

Ideal SiC devices for power applicationsIdeal SiC devices for power applications

2.35Å

1.89Å

Breakdown voltage [kV]

On-

stat

e vo

ltage

[V]

1

10

1010.1

Low loss, high voltage Low loss, high voltage SiC devicesSiC devices

SiC-MOSFETSi-MOSFET

Si-IGBT

Si-GTO

SiC-IGBT

Merits of SiC Devices

Physical parameters of different materials and expectations from SiC

Physical parameters of different materials and expectations from SiC

Material BandgapEnergyDielectricConstant

ElectronMobility

BreakdownElectric Field

SaturatedElectron Drift

Velocity

ThermalConductivity

Eg εr μn Εc νsat λeV (dimension) cm2/Vｓ 106Ｖ/cm 107cm/s W/cm.K

Si 1.1 11.9 1500 0.3 1.0 1.5GaN 3.4 9.5 900 2.6 2.5 1.33C-SiC 2.2 9.7 800 3.0 2.7 4.94H-SiC 3.0 9.7 1000 3.5 2.7 4.96H-SiC 2.9 9.7 460 3.0 2.0 4.9

• MOSFET-like fast speed

• Lower power loss• Higher junction temperature

Low On-resistance (approx. 1/100 of Si）

High temp. operation (approx. 3x of Si)

High Breakdown Voltage (approx. 10x of Si)

High Thermal Conductivity (approx. 10x of Si)

Loss reductionDown sizingCost reduction

System Merits

Cap

acity

of a

pplie

d sy

stem

(VA

)

Operation frequency (Hz)

AutomotiveInverter

UPS

DC transmission

Steel mill traction

• Higher voltage > 10kV• Higher current density

• Voltage driven device (MOS-gated)• Higher voltage, higher current• On-state resistive loss reduction

• MOSFET-like fast switching speed• Simple forced air cooling realized

by higher Tj operation

4H-SiC : Silicon

FOM【λ＊Johnson FOM】

【 λ＊（Ec＊sat）2ע 】

1407238132411307

gatesource

drain

n-drift layer

n-SiC substrate

Al-implanted p-body

p-bodycontact

epi-layer channel

Silicon Carbide R & D status Silicon Carbide R & D status

4H-SiC Double Implanted OSFETVBr=1900V Ron=40mΩcm2

1. High voltage vertical structure

2. Double implantation3. Epilayer channel

-High quality-Doping control

4. JTE termination

4H-SiC Schottky Barrier DiodeVBr=1500V Ron=3mΩcm2

High Temp Epitaxial Growth

Spe

cific

on-

resi

stan

ce(m

Ωcm

2 )

500 1000 20001

10

100

5000

Mitsubishi Mitsubishi (2002)(2002)

SiSi--limitlimit 1/10 of Si-limit1/100 of Si-limit

SiCSiC--limitlimit

MOSFETSchottky

4H 6HSiC

Mitsubishi Mitsubishi (2002)(2002)

Previous work Previous work (2002)(2002)

Previous work Previous work (2002)(2002)

Breakdown voltage (V)

Ron = 40mOhm.cm2 BV = 1900V

Electrical characteristics of initial4H-SiC Power MOSFET test element

-2

0 1000 20000

6x10

1x10

4x10

2x10

8x10

-3

-3

-3

-3

Drain-Source Voltage (V)

Vg=0V

Vb=1900Vドレイン電流

(mA)

Ron=40mΩcm2

0 1 20

10

20

Dra

in c

urre

nt (m

A)

Vg=25VVg=20V

Vg=15V

Vg=10V

Vg=0.5V

Drain-Source Voltage (V)

Initial work (2002)Initial work (2002)

Breakdown voltage (V)

Spe

cific

on-

resi

stan

ce(m

Ωcm

2 )

500 1000 20001

10

100

5000

Mitsubishi

Mitsubishi 2002

Si-limit 1/10 of Si-limit 1/100 of Si-limit

SiC-limit

mobility=20cm2/Vs channel length=3µm

mobility=100cm2/Vs channel length=3µm

mobility=100cm2/Vs channel length=1µm

MOSFETSchottky

Mitsubishi 2001

Silicon Carbide R & D goalsSilicon Carbide R & D goals

SiC MOSFET Cell Structure

4H-SiC High Voltage MOSFET

Al source electrodes

Gate Pad

１mm

New SiC High Voltage MOSFET Development

(Performance :1200V, 13mΩ・cm2)

(Experimental chip)

Contact Hole

Source AreaChannel Area

p+

n+ SiC Substrate

Drain Metal

n+p++

Poly Si Gate

Source Metal

Epitaxial Channel

２５μmGate length: 2μm

n- Epitaxial Layer

p+p++n+

Present target (2004)Present target (2004)

Silicon Carbide R & D goalsSilicon Carbide R & D goals

Performance of a 30A/600V 4HSiC-SBD chip (experimental)

●Compact PFC-Inverter system●Complete clear of harmonic

current regulation● High performance PAM control● High system efficiency

●Compact PFC-Inverter system●Complete clear of harmonic

current regulation● High performance PAM control● High system efficiency

R

S

LVIC

Q1Q2

N

N2

P

N/F

HVIC HVIC HVIC LVIC

MCUControlIC

P

N

M

Relay

Co Co’’Co’

ACL

(controllable)DC 300-400V

PFC Circuit Inverter Circuit

DIP-IPM

AC 90-264V

Preferable device: SiCPreferable device: SiC--SBDSBD

(High frequency, Low loss requirement)

(universal)

Possible module packagingPossible module packaging

DIP-IPM

Use of DIP-IPM concept

DIP-PFC

SiC application example (Future)SiC application example (Future)

High performance PFC-Inverter for Air-conditioning

0.00

0.20

0.40

0.60

0.80

1.00

1.20

75 100 125 150 175 200 225 250 275

Junction Temp. [℃]

Inve

rter O

pera

tion

Loss

［R

atio

］- based on simulation using 1200V device designs -

- Predicted system benefits -

High temp. operation will allow chip size reduction and attribute to lower power losses, simultaneously.

System Cost Reduction

• Higher power density• Simpler hardware for

thermal management

Si-CSTBT＋Si-FWDiDevice active area : 1

SiC-MOSFET＋SiC-SBDDevice active area

0.250.50

0.16

Conditions for Simulation:Vcc=600V, Irms=31A, Modulation ratio=1.0Power Factor=0.8, fc=20kHz (Sinusoidal PWM)SiC-MOSFET Ron=5mΩcm2@25℃ (Note-2)SiC-SBD Ron=3mΩcm2@25℃ (Note-2)Note:1) Exsisting Silicon-IGBT based system's device loss at Tj=125℃/fc=20kHz operation is referenced as unity for comparison.2) Assumed values for simulation purpose.

0.00

0.20

0.40

0.60

0.80

1.00

1.20

75 100 125 150 175 200 225 250 275

Junction Temp. [℃]

Inve

rter O

pera

tion

Loss

［R

atio

］

- Predicted system benefits -- based on simulation using 1200V device designs -

SiC-MOSFET＋SiC-SBDDevice active area ：0.25

Si-CSTBT＋Si-FWDi(limited to roughly 20kHz)Device active area : 1

Adoption of high frequency control

Reduces size/weight of peripheral components

System Cost Reduction

20ｋHz

50ｋHz

100ｋHz

Conditions for Simulation:Vcc=600V, Irms=31A, Modulation ratio=1.0Power Factor=0.8, fc=Vriable (20-100kHz)SiC-MOSFET Ron=5mΩcm2@25℃ (Note-2)SiC-SBD Ron=3mΩcm2@25℃ (Note-2)SiC device active area = 25% of Si-IGBT device active areaNote:1)Existing Silicon-IGBT based system's device loss at Tj=125℃/fc=20kHz operation is referenced as unity for comparison.2) Assumed values for simulation purpose.

33--ph inverter using siliconph inverter using silicon(state-of-the-art)

Cooling fans Forced air-cooling Natural air-cooling

SiC-MOSFET Module(Dual 100A/1200V)

Volume ratio = 1/3Volume ratio = 1/3PowerPower--loss ratio = 0.loss ratio = 0.44

Si-IGBT Module(5th Gen. Dual 100A/1200V)

33--ph inverter using SiCph inverter using SiC(Future prediction)

Operating Operating TjTj = 125 deg. C= 125 deg. C

Operating Operating TjTj = 250 deg. C= 250 deg. C

- Predicted system benefits -Si vs. SiC comparison for 460V/22kW/3-ph MC

600 VHome Appliances（refrigerator, air-conditioner, and washing

machines）

Automotive (EV, HEV, and FCV)Elevators, UPS and Factory Automation,Power supplies, Alternative energy sources

600-1700 V

Electric Railway Systems, Metal Industries 1200-6500 V

Motor Controls and Power Supplies

Voltage RatingsApplications

600-1200 V

Power network, Utilities > 10kV

Predicted Major Applications of SiC-MOSFET Predicted Major Applications of SiC-MOSFET

1

2

3

4

5

6

1995 1997 1999 2001 2003 2005 2007 2009 2011

Year

Wafer Diameter(inch）

0

5

10

15

20

25

30

MPD

(cm

-2)

(Data from ICSCRM 2001)

Diameter ADiameter BDiameter C

Pipe density (MPD) for A

(1)(1) Pipe density reductionPipe density reduction(2) Wafer diameter increment

The key issues and projectionsThe key issues and projections

Reliability issue High grade

High voltageHigh powerHigh cost

Uninterruptible Power Supplies

(UPS)600V-1200V

Motor Drives for Industry600V-1200V

Traction, Large Motor Drives

>1700V

Power Transmission> 5000V

Higher reliability, Simpler system design, Safer Operation

Normally Off type preferred

Home Appliances

2002 2003 2004 2005 2006 2007 2008

Denominations :LPT-CSTBT: Light Punch-through CSTBT MPS-Diode : Merged PiN Schottky DiodeSiC-FET : Silicon Carbide FET SiC-SBD : Silicon Carbide Schottky Barrier Diode

(FY)

Func

tions

/ Pe

rfor

man

ceFu

nctio

ns /

Perf

orm

ance

New Ma

terial

New Ma

terial

Key Power DevicesKey Power DevicesSiC-FET, SiC-SBD,Intelligent devices

Key ProcessesKey ProcessesSiC wafer processHi-speed epitaxial growthHi-grade oxide formation )

Power Device Development RoadmapPower Device Development RoadmapPower Device Development Roadmap

Versati

lity

Versati

lityKey ProcessesKey ProcessesDeep-Trench StructureUltra-thin waferBackside diffusionMulti-layered connections

Key Power DevicesKey Power DevicesReverse Conducting IGBTReverse Blocking IGBTIntelligent devices

Proces

s Refin

e

Proces

s Refin

eKey ProcessesKey Processes

Sub-micron Cell-Trench StructureThin wafer

Key Power DevicesKey Power DevicesLPT-CSTBTMPS-DiodeSub-micron MOSFET

and